In order to improve the automation level of automatic weather station testing work and simplify the adjustment of the PTB220 barometer, the working principles of PTB220 are analyzed. By using the parts of the 3MS system hardware, the automatic adjustment function of indication errors is realized based on the automatic response technology of serial communication. In this paper, the principles and operation flow of digital quantity and analog quantity adjustments are expatiated in detail. The configuration of the serial communication parameter and the example of source codes are given for example and the feasibility of the system design is verified by actual operation